1. Field of the Invention
The present invention relates to a power supply device for reducing switching loss.
2. Description of the Related Art
Recently, active power factor correction technologies, necessarily used in an alternating current (AC)-direct current (DC) power supply device having high capacity have come to prominence in connection with improvements of the stability and power quality of power supply devices. In addition, various topologies and control technologies have been grafted onto active power factor correction technologies.
A boost power factor correction (PFC) circuit including one inductor, one power semiconductor switch, and one diode, has been most commonly used in an active power factor correction field. However, it may be difficult to apply the boost PFC circuit to an AC-DC power supply device having a high capacity of 1 kW or more, due to relatively low efficiency, high levels of voltage ripple, and electro-magnetic interference (EMI) noise.
In order to address the defect of such a general boost PFC circuit and to apply the boost PFC circuit to an AC-DC power supply device having high capacity, a bridgeless boost PFC converter has been suggested.
A bridgeless boost PFC converter does not use a rectifier on an input terminal, thereby reducing costs for the implementation of the PFC circuit. In addition, a bridgeless boost PFC converter may increase efficiency by removing conduction loss that may be generated in a bridge rectifier.
However, a bridgeless boost PFC converter may have a high conducted common mode EMI noise level due to high input ripple current and switching of PFC switch parasitic capacitance connected to the ground. Accordingly, the bridgeless boost PFC converter requires a very large EMI filter, which increases costs of the bridgeless boost PFC converter and reduces power density of the converter.
In particular, conventionally, in order to implement an isolated AC-DC power supply device, a two-stage configuration formed by connecting a non-isolated bridgeless boost PFC converter and an isolated DC-DC converter is used. However, the two-stage configuration may increase costs and power loss due to the two-stage configuration. In order to address the defect, research into various isolated AC-DC converters having single-stage structures has been conducted.